1. Field of the Invention
The present invention relates to a transfer picture re-transferring member used for re-transferring a formed toner image onto a re-transfer medium. More particularly, the present invention relates to a transfer picture transferring member used for re-transferring a toner image formed by an electrophotographic unit or an electrostatic recording unit, and a toner image re-transferring method using the same.
2. Description of the Related Art
Three-dimensionally transferring an image by the use of a transfer picture technique is known: the commonly-known conventional water pressure transferring method comprises the steps of coating a water-soluble paste as typically represented by dextrin onto a substrate such as a sheet of paper, forming a desired image on the coated film using an acrylic ink by screen printing or the like, dissolving dextrin by dipping the image-bearing paper into water, and transferring the acrylic ink image floating on water onto a three-dimensional object such as china. In an example of direct application of the transferring paper used in this method to electrophotography, re-transferring is accomplished by the steps of preparing a transferring member by forming a dextrin film on the sheet of rice paper, forming a toner image on the surface of dextrin by means of an electrophotographic unit, then, passing the transferring member through an organic solvent capable of causing a resin in the toner to soften, imparting to the toner image adhering power to a transfer medium onto which re-transferring is to be made (hereinafter referred to the “re-transfer medium”), bringing the transferring member into contact with the re-transfer medium so that the toner image is in direct contact with the re-transfer medium, and then, supplying water from the back of the paper to dissolve the dextrin film, thereby transferring only the toner image.
Japanese Patent Laid-Open No. 4-361,086 proposes a transferring member using polyvinyl alcohol, a saponified vinyl acetate, in place of dextrin. The transferring member comprises a silicone resin coated onto paper, an acrylic resin layer formed thereon, and further, a mixture of CASSESOL made by the Nikka Kagaku Company and a silicone antifoaming agent coated thereon. Re-transferring is accomplished by forming a toner image on the coated film by means of an electrophotographic unit, then stripping off the CASSESOL film from the substrate, and bringing the toner image into direct contact with the re-transfer medium.
Adhesion to the re-transfer medium is obtained by causing the resin contained in the foregoing toner image by heating and applying a pressure, and an aqueous 80% ethyl alcohol solution is applied from the back of the CASSESOL film after cooling to reduce adhesion between the CASSESOL film and the toner image, thus completing re-transferring.
Another transfer picture technique of re-transferring an image formed by an electrophotographic unit onto a re-transfer medium is disclosed, for example, in Japanese Patent Laid-Open No. 52-82,509. A transfer medium used in this transfer picture is available, for example, by forming an undercoat layer comprising methyl methacrylate-n-butyl copolymer, polyvinyl acetate homopolymer emulsion, vinyl chloride homopolymer latex, and/or vinyl chloride acrylate latex, alone or in combination, on a paper or plastic film having a stripping layer having a high strippability, comprising a silicone resin or a fluororesin, formed thereon.
The subsequent steps comprise forming a toner image on the thus completed transferring member in an electrophotographic unit, applying a fixing operation at least to an extent that the tone does not peel off, heating, and applying a pressure to, the transferring member after fixing while bringing the same into contact with the re-transfer medium (cloth, etc.) so that the toner image is in direct contact with the medium, until the toner and the undercoat layer of the transferring member soften, cooling the assembly, and stripping off the paper or the like having a stripping layer while leaving the toner image and the undercoat layer on the transferring member side, thus completing re-transferring.
In these cases, however, the paper is exposed on the back, and consequently, the paper may sometimes suffer serious curling, depending upon the environment in which the transferring member is left.
In view of these circumstances as described above, a technique is proposed, which prevents curling by forming a resin lining layer.
However, when forming a high-bridging resin simply into a filler layer, the water feed rate of resin differs between the copied and non-copied sides of the paper, and upon unpacking the paper, serious curling occurs to make it impossible to feed the paper within the electrophotographic unit.
Particularly, when the copied side is formed with a polymer material hardly susceptible to the effect of humidity such as a vinyl resin, a polyurethane resin, an epoxy resin or a polyamide resin, or when the back side is formed by impregnating with a resin (paper fibers are exposed), or formed with a polymer easily susceptible to the influence of humidity, serious curling is caused.
When the same resin is used for the surface and the back, a high affinity of resin results in simultaneous feed of two or more sheets.